PROJECT SUMMARY The candidate, Dr. Ali Zarrinpar, presents a 5-year career development plan that seeks to characterize the relationship between pre-transplant neutrophil activity, ischemia/reperfusion injury (IRI), and eventual transplant outcomes while establishing an academic career as a physician-scientist in the field of surgery. IRI is the principal mechanism by which diseases such as myocardial infarction, stroke, and peripheral vascular disease cause their damage. It is also a major source of graft injury during organ transplantation. He and his colleagues have found that Bruton's tyrosine kinase (Btk) activity is important in liver IRI. Its selective inhibition blocks IR-induced hepatocellular damage and as a result protects the liver from subsequent severe inflammation. They also have conducted studies using specimens from human liver transplant recipients and found cytokines present in pre-transplant sera of recipients that predict the severity of IRI. These data suggest that recipients' pre-transplant immunologic milieu can influence IRI. These data have led them to hypothesize that measuring and modulating pre-transplant neutrophil activity will permit the selection, monitoring, and modulation of IRI, thereby improving liver transplant outcomes. This hypothesis will be pursued with two specific aims that investigate the relationship between neutrophil activity and IRI. Specific aim 1 tests the hypothesis that Btk activation potentiates neutrophil activation and promotes innate immune activity. This hypothesis will be tested both in vitro and in vivo using murine models. Specific aim 2 tests the hypothesis that heightened neutrophil activity before transplantation leads to increased IRI and subsequent activation of resident Kupffer cells and recruitment/activation of monocytes/macrophages and circulating T cells in human liver allografts, and that this pathological cascade perpetuates damage to the graft. This hypothesis will be tested using samples from human liver transplantation operations. Dr. Zarrinpar is well qualified to carry out the research outlined in this proposal. He has successfully completed projects of comparable complexity as part of his PhD thesis. He will train further by acquiring expertise in high quality IRI experiments and by studying immunology and cell biology. His mentor Dr. Jerzy Kupiec-Weglinski has decades long experience in studying transplant immunology and IRI. His co-mentor Dr. Stephen Bensinger provides expertise in studying the cell biology, signaling, and metabolic factors affecting the immune response. Dr. Ronald Busuttil, who has extensive experience training academic surgeons, will advise him on major career related issues and help navigate the academic promotion process. He will meet with his mentor and co-mentor monthly and meet with his surgical mentor every three months to discuss progress and to ensure a successful scientific program. Successful completion of the specific aims and career development plan outlined in this proposal will allow Dr. Zarrinpar to learn how to perform high quality immunology studies and to develop into an independent investigator in the field of surgery and immunology.